Electrical Machines
Which of the following represents the commutator pitch?

 The distance between the staring of first coil and its next successive coil
 Number of conductors spanned by one coil at the front end of the armature.
 Number of commutator segments between two successive coils.
 Number of conductors spanned by one coil at the back end of the armature.

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Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

 field winding was wrongly connected
 there was a break in the armature circuit
 field resistance was higher than critical resistance
 there was no residual magnetism in the field circuit

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